Voltage regulation circuits can accept input power from a variety of sources such as batteries, mains supplies, or other sources. Voltage regulation circuits generally provide a regulated output parameter, such as a regulated output voltage, having a specified output accuracy over a specified range of input, load, and environmental conditions. Such regulation circuits can be implemented using a variety of circuit topologies. For example, linear regulators generally control an output parameter using one or more of a series element (e.g., a pass transistor) or a shunt element (e.g., a shunt transistor). The series or shunt element can be controlled to modulate current flow or an output voltage across a range of values using a linear control scheme, generally where the series or shunt element is dissipative. Such dissipative losses can make linear regulators inefficient in comparison to other approaches.
Other regulator topologies, such as switched-mode regulators, can operate by toggling one or more series or shunt elements between fully-conducting and cut-off states. Generally, switched-mode voltage regulation circuits can perform voltage conversion to provide an output voltage that is below an input voltage magnitude (e.g., a buck topology), or an output voltage that is above the input voltage magnitude (e.g., a boost topology), or both (e.g., a buck/boost topology). Because the switching elements in a switched-mode regulator are not operated in an intermediate conductive state between cut-off or fully-conducting, dissipative losses in a switched-mode regulator may be lower than a linear regulator.
By contrast, low dropout (LDO) regulator circuits are a class of linear regulators that can be used to provide one or more of high output parameter accuracy across a range of conditions or tolerance of significant voltage excursions at the input. Such LDO regulators may be referred to as precision voltage regulators. LDO regulators may exceed the performance of switched-mode regulators in terms of output voltage accuracy or precision across a range of conditions.